1. Field of the Invention
The present invention relates to a method of repairing automatically the cracks in a member to be repaired and an apparatus for use in such a method, specifically a method of repairing automatically the cracks produced in a blade, etc. of a rotary machine and an apparatus for use in such a method.
2. Description of the Related Art
Generally, cracks tend to occur in a blade, etc. of a rotary machine (for example in a turbine blade) owing to the severe environment of operation. Therefore, it is required in the operation of a turbine, etc. to periodically check if a crack is produced or not. To be concrete, the blades are checked after the operation of the turbine, and if a crack is found, the crack is repaired.
Recently, apparatuses for automatic welding have been developed. Welding can be carried out automatically by the use of such an automatic welding apparatus. However, in the case of repairing cracks, the states of cracks are diverse and it is difficult to repair the cracks by using an automatic welding apparatus. To be more specific, when repairing cracks by welding, the welding must be performed according to the direction, position, depth, etc. of the cracks, so the repair of cracks by an automatic welding apparatus has been difficult.
Therefore, the repair of the crack produced in the blade, etc. has been carried out by handwork, in which the position, width, depth, etc. of the crack are recognized by hand, the aperture of the crack is ground, then the ground portion is welded by hand welding.
When the crack has been repaired, as has been described above, by handwork, recognizing by hand the position, width, depth, etc., grinding the aperture of the crack, then welding the ground part by hand welding, a proficiency has been required in the repair, and in addition, the grinding and welding should have been carried out according to the result of careful examination of the crack. Therefore, when considering the diversity of the states of cracks, the number of processes inevitably increases for repairing the crack produced in a member to be repaired such as a blade, etc.
Further, since skill is required for repairing cracks as mentioned above, the result of repair is dependent on the skill of a welder, so there occurs the problem that stable quality of the repaired part is not assured.
To overcome the disadvantage mentioned above, an invention was disclosed in Japanese Patent Application Publication No. 9-145340, for example, for reducing the man-hours required to detect and measure cracks at inspection or for automatization of these steps concerning gas turbine blades.
According to the disclosure, the apparatus is composed of, as shown in FIG. 7(A), a detector (camera) 121 to detect cracks, a driver 122 to drive the detector, a position controller 123 to control the position of the driver, an image processing apparatus 124 to process the image information of the surface of a stator vane input from the detector, a calculation operation unit 125 to determine the degree of damage such as the maximum crack length, sum of crack lengths, etc. by measuring crack lengths from the processed image, and a memory 126 to store the data of the shapes of stator vanes. With the apparatus, the detected image of a crack is divided properly, and the coordinates of each point of division c1, c2, c3, . . . are projected on real shape model to determine the real crack length, as shown in FIG. 7(B).
However, in the art mentioned above, the measurement in the case of a branched crack is not taken into consideration. Further, when projected in a wide field of vision, the depth of the crack can not be determined, and when projected in a narrow field of vision, the path of the crack can not be judged. As a result, the accuracy of determination of cracks decreases.